CN101395243B - Refrigerant composition - Google Patents

Abstract

A refrigerant composition consisting essentially of three hydrofluorocarbon components selected from the group consisting of HFC134a, HFC125 and HFC143a and an additive selected from the group consisting of Saturated or unsaturated hydrocarbons or mixtures thereof.

Description

Refrigerant composition

The present invention relates to refrigerant compositions. In particular, the present invention relates to refrigerant compositions which do not adversely affect stratospheric ozone. The present invention also relates to compositions for use in refrigeration and air conditioning systems designed for the use of ozone depleting substances (ODS), including HCFC22 (chlorodifluoromethane), and for novel equipment. These refrigerant compositions are compatible with lubricants commonly used in refrigeration and air conditioning systems, as well as newer synthetic lubricants such as polyol ester oils.

Although considerable care is taken to prevent the refrigerant from escaping into the atmosphere, this happens from time to time. Hydrocarbon emissions are controlled in some regions in order to minimize the generation of tropospheric ozone due to the mixing of hydrocarbons and oxygen under the action of sunlight. To minimize the effect of hydrocarbons on the atmosphere due to leakage of the compositions referred to in the present invention, the hydrocarbon content should preferably be less than 5%, more preferably less than 3.5%.

The compositions of the present invention may also be used in equipment designed for non-ozone depleting substances.

It is well known that although chlorofluorocarbons (CFCs) such as CFC12 and CFC502 and hydrochlorofluorocarbons such as HCFC22 are energy-efficient, non-flammable and low in toxicity, these substances migrate to the stratosphere where they are and break down to attack the ozone layer. It is desirable to replace ODS with non-ozone-depleting alternatives such as hydrofluorocarbons (HFCs), which are also non-flammable, energy-efficient and less toxic. There are six main HFCs, namely HFC134a, HFC32, HFC125, HFC143a, HFC227ea and HFC152a, which can replace CFCs and HCFCs either alone or in mixture. HFC134a, HFC227ea and HFC152a can be used directly to replace ODS, while HFC32, HFC143a and HFC125 are usually used in mixtures to replace ODS. However, because HFCs do not have sufficient solubility in conventional lubricants such as mineral oils and alkylbenzene oils, synthetic oxygen-containing lubricants have been specifically introduced into new types of equipment. These new lubricants are expensive and hygroscopic.

Refrigerant blends such as R404A, R507, R410A, R407C and others have been commercialized as substitutes for CFCs and HCFCs. However, because these compositions include only HFC components, they cannot be used with conventional lubricants that are often used with CFCs and HCFCs. If these blends are used to replace CFCs and HCFCs in existing equipment, large chemical manufacturers recommend keeping no more than 5% of conventional lubricants in the system, which may require an almost complete lubricant change to synthetic oxygenated lubricants, Even completely refurbish the system. This is often expensive and technically unsatisfactory.

Although equipment manufacturers have adapted their plants to work with HFC blends, commercially available HFC products have been found to be less satisfactory than CFCs and HCFCs. In particular, hydrocarbon lubricants such as mineral oils have been replaced by oxygen-containing lubricants, especially polyol esters and polyalkylene glycols, in order to ensure adequate oil return. Unfortunately, these materials tend to absorb moisture from the atmosphere, especially during maintenance; this moisture can cause excessive corrosion and wear of the equipment, reducing the durability of the equipment. It is an object of the present invention to provide HFC/hydrocarbon mixtures which allow the continued use of hydrocarbon oils in both existing and new installations.

When looking for a refrigerant blend that can easily be used to replace R22 in new and existing equipment, it is especially important that the new blend has sufficient cooling capacity. This capacity should be at least 90%, preferably at least 95% of the fluid it replaces, most preferably equal or greater than the fluid it replaces under similar operating conditions. The refrigerant composition according to the present invention has a capacity similar to that of R22 in the range of high- to low-temperature air-conditioning and refrigeration applications in which R22 is generally used.

Some refrigerants, such as R407C, have a wide temperature glide (>4°C) in the evaporator and condenser. Equipment manufacturers prefer to choose refrigerants with low temperature glide based on their experience with CFC/HCFC single fluids or azeotropic mixtures. Another object of the present invention is to provide HFC/hydrocarbon mixtures that can replace HCFC22 and HFC mixtures (such as R407C), so that hydrocarbon lubricants can continue to be used in equipment, and by providing azeotropic mixtures and near azeotropic mixtures Minimize temperature glide in heat exchangers.

Various terms are used in the patent literature to describe refrigerant mixtures. The following definitions are taken from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 34;

Azeotrope: An azeotrope is a mixture of two or more refrigerants whose composition is the same in the equilibrium vapor and liquid phases at a certain pressure. Azeotropes exhibit some degree of separation of components under other conditions. The degree of separation depends on the particular azeotrope and its application.

Azeotropic temperature: At a specific pressure, the temperature at which the components in the liquid phase and the components in the gas phase of a mixture in equilibrium have the same mole fraction.

Near-azeotropic mixture: A non-azeotropic mixture in which the temperature glide is so small that it can be ignored without causing errors in the analysis of a specific application.

Zeotrope: A mixture of components of differing volatility which, when used in a refrigeration cycle, evaporate (boil) or condense at constant pressure, changing volumetric composition and saturation temperature.

Temperature glide: The absolute value of the difference between the temperature of the refrigerant at the beginning and end of the phase change process within the unit of the refrigeration system, excluding any subcooling or superheating. The term is often used to describe the condensation or evaporation of a zeotropic mixture.

The present invention relates to near-azeotropic and zeotropic refrigerant compositions which are non-flammable under all fractionation conditions as defined by ASHRAE Standard 34 and which can be used to replace ODS in existing units without changing the lubricant, and No significant changes to the system hardware are required. These refrigerant compositions allow the continued use of hydrocarbon oils in new equipment, but also allow modifications to the unit such as selection of the most appropriate capillary length to optimize the performance of the new refrigerant. The novel composition allows the hydrocarbon oil to replace the oxygenated oil in the event of moisture ingress or other problems.

It is known in the art that the addition of small amounts of hydrocarbons to refrigerant compositions containing HFCs or mixtures of HFCs will dissolve enough hydrocarbons in the lubricant transported through the system to maintain lubrication of the compressor at all times. Clearly, the greater the amount of hydrocarbons in the composition, the greater the ability of the refrigerant to deliver the lubricant back to the compressor. However, too high a hydrocarbon content can result in a combustible mixture. While flammable refrigerants are acceptable in certain applications, the present invention is directed to non-flammable compositions for use in equipment that prohibits the use of flammable refrigerants. However, it is less clear how non-flammable compositions can be obtained under all conditions, including those that produce fractional distillation of the refrigerant composition when the refrigerant leaks from the system or during storage. Flammability in both the liquid and gas phases needs to be considered.

Not all HFCs are non-flammable as defined by ASHRAE Standard 34. HFC143a and HFC32 have not been rated by ASHRAE for non-flammability. The present invention relates to refrigerant compositions comprising not only mixtures of non-flammable HFCs and hydrocarbons in selected proportions, but also mixtures of flammable HFCs, non-flammable HFCs and hydrocarbons in selected proportions; all of these mixtures in fractional distillation Both are nonflammable, and these blends provide similar refrigeration and thermodynamic performance to the ODS and HFC blends they replace.

While the present invention relates to refrigeration compositions that can be used with traditional lubricants such as mineral oils and alkylbenzene oils, it is also suitable for use with synthetic oxygen-containing lubricants.

When formulating HFC/hydrocarbon mixtures to replace HCFC22 in specific applications, it is sometimes necessary to use one or more high boiling HFCs together with one or more low boiling HFCs. The preferred low boiling HFCs in this case are HFC143a and HFC125, and the high boiling HFC is HFC134a.

To prevent the flammability of mixtures or fractions as defined by ASHRAE Standard 34 from spills, the total amount of hydrocarbons should be minimized. At the same time, the amount of hydrocarbon mixture dissolved in the oil needs to be maximized to allow good oil return, especially in areas of the circuit where the oil viscosity is greatest, such as in the evaporator. One of the HFC components of the present invention, HFC 143a, is classified on ASHRAE safety classification A2, which makes the amount of HFC 143a and the choice of hydrocarbons very critical in obtaining the non-flammable rating A1 of the mixture. Single higher boiling hydrocarbons such as pentane or isopentane will concentrate in the liquid phase. This was demonstrated by leak testing the mixture of HFC134a, HFC125 and pentane shown in Example 1.

According to the National Institute of Standards and Technology (NIST) program Refleak (which is widely used to determine the fractionation of refrigerant mixtures under all conditions specified in ASHRAE Standard 34), the determination of HFC134a, HFC143a and R125 with butane and iso Butane mixtures produced the results shown in Example 2. Near the end of the leak, there was a significant increase in butane in the liquid phase of more than 60%, compared to only about 15% increase in isobutane.

Mixtures of isobutane alone with HFC134a, HFC143a, and R125 were also tested according to the Refleak procedure, and the results are shown in Example 3. Under the most unfavorable fractionation conditions, the increase in isobutane in the liquid phase is shown to be much less than the increase in butane. In EP1238039B1, Roberts teaches not to include 2-methylpropane (isobutane) in mixtures containing HFCs due to concerns about flammability under the most unfavorable fractionation conditions. Surprisingly, we have found that the use of isobutane in mixtures comprising HFC134a, HFC143a and HFC125 results in nonflammability under ASHRAE Standard 34 under the most unfavorable fractionation conditions.

The present invention allows a flammable HFC such as HFC 143a to be used in a non-flammable refrigerant mixture thereby greatly improving its performance, especially its capacity.

The refrigerant composition according to the present invention consists essentially of a hydrofluorocarbon component and an additive, the hydrofluorocarbon component consisting of a mixture of:

R134a, R125 and R143a

The additives are selected from saturated or unsaturated hydrocarbons or mixtures thereof boiling in the range of -50°C and +40°C.

In preferred embodiments, the composition comprises a mixture of hydrofluorocarbon components and hydrocarbon components, in the absence of any other components or other gases in substantial amounts.

In a more preferred embodiment, the hydrocarbon is present in an amount of 0.1 to 5% and is non-flammable when the composition is entirely in the gas phase.

In another more preferred embodiment, the amount of the hydrocarbon is from 0.1 to 5%, and when both the liquid and the gas of the composition are present in the same container, neither the gas phase nor the liquid phase is flammable.

The hydrocarbon additive may be selected from 2-methylpropane, propane, 2,2-dimethylpropane, n-butane, 2-methylbutane, cyclopentane, hexane, ethane, 2-methylpentane Alkanes, 3-methylpentane, 2,2-dimethylbutane, methylcyclopentane, propylene, n-butene, isobutene and mixtures of the above.

In another embodiment, a refrigerant composition that can be used to replace R22 includes:

(i) about 10 to 35 weight percent HFC134a, preferably 10 to 25 weight percent HFC134a; and

(ii) about 30 to 79.9 weight percent HFC125, preferably 46 to 74.7 weight percent HFC125; and

(iii) about 10 to 30 weight percent HFC143a, preferably 15 to 25 weight percent HFC143a; and

(iv) about 0.1 to 5 weight percent butane or isobutane or propane, preferably 0.3 to 4 weight percent butane or isobutane or propane.

In another embodiment, a refrigerant composition that can be used to replace R22 includes:

(i) about 10 to 35 weight percent HFC134a, preferably 10 to 25 weight percent HFC134a; most preferably 15 to 20 weight percent HFC134a; and

(ii) about 25 to 79.8 weight percent HFC125, preferably 42 to 74.4 weight percent HFC125; most preferably 53 to 67.4 weight percent HFC125; and

(iii) about 10 to 30 weight percent HFC143a, preferably 15 to 25 weight percent HFC143a; most preferably 17 to 22 weight percent HFC143a; and

(iv) a mixture of about 0.1 to 5 weight percent butane and about 0.1 to 5 weight percent isobutane or a mixture of butane (0.1 to 5%) and isopentane (0.1 to 5%) or butane ( 0.1 to 5%) and propane (0.1 to 5%) or a mixture of isobutane (0.1 to 5%) and propane (0.1 to 5%), preferably 0.3 to 4 weight percent butane (0.3 to 4%) and isobutane (0.3 to 4%) or butane (0.3 to 4%) and isopentane (0.3 to 4%) or butane (0.3 to 4%) and propane ( 0.3 to 4%) or a mixture of isobutane (0.3 to 4%) and propane (0.3 to 4%), most preferably 0.3 to 3 weight percent isobutane and 0.3 to 2 weight percent propane or a mixture of 0.3 to 3 weight percent butane and 0.3 to 2 weight percent propane.

In another embodiment, a refrigerant composition that can be used to replace R22 includes:

(i) about 10 to 35 weight percent HFC134a, preferably 10 to 25 weight percent HFC134a; and

(ii) about 20 to 79.7 weight percent HFC125, preferably 38 to 74.1 weight percent HFC125; and

(iii) about 10 to 30 weight percent HFC143a, preferably 15 to 25 weight percent HFC143a; and

(iv) a mixture of about 0.1 to 5 weight percent butane and about 0.1 to 5 weight percent isobutane and about 0.1 to 5 weight percent propane, preferably 0.3 to 4 weight percent butane (0.3 to 4%) and A mixture of isobutane (0.3 to 4%) and propane (0.3 to 4%).

A composition that can be used to replace R22 mainly includes:

R134a 16%

R125 60%

R143a 21%

Isobutane 2%

Propane 1%

Another composition that can be used to replace R22 mainly includes:

R134a 16%

R125 60%

R143a 21%

Butane 2%

Propane 1%

A preferred composition mainly includes:

R134a 10 to 35%

R125 79.9 to 30%

R143a 10 to 30%

Butane 0.1 to 5%

A preferred composition mainly includes:

R134a 10 to 25%

R125 74.7 to 46%

R143a 15 to 25%

Butane 0.3 to 4%

A preferred composition mainly includes:

R134a 10 to 35%

R125 79.9 to 30%

R143a 10 to 30%

Isobutane 0.1 to 5%

A preferred composition mainly includes:

R134a 10 to 25%

R125 74.7 to 46%

R143a 15 to 25%

Isobutane 0.3 to 4%

A preferred composition mainly includes:

R134a 10 to 35%

R125 79.9 to 30%

R143a 10 to 30%

Propane 0.1 to 5%

A preferred composition mainly includes:

R134a 10 to 25%

R125 74.7 to 46%

R143a 15 to 25%

Propane 0.3 to 4%

A preferred composition mainly includes:

R134a 10 to 35%

R125 79.8 to 25%

R143a 10 to 30%

Butane 0.1 to 5%

Isobutane 0.1 to 5%

A preferred composition mainly includes:

R134a 10 to 25%

R125 74.4 to 42%

R143a 15 to 25%

Butane 0.3 to 4%

Isobutane 0.3 to 4%

A preferred composition mainly comprises:

R134a 10 to 35%

R125 79.8 to 25%

R143a 10 to 30%

Butane 0.1 to 5%

Isopentane 0.1 to 5%

A preferred composition mainly includes:

R134a 10 to 25%

R125 74.4 to 42%

R143a 15 to 25%

Butane 0.3 to 4%

Isopentane 0.3 to 4%

A preferred composition mainly includes:

R134a 10 to 35%

R125 79.8 to 25%

R143a 10 to 30%

Butane 0.1 to 5%

Propane 0.1 to 5%

A preferred composition mainly includes:

R134a 10 to 25%

R125 74.4 to 42%

R143a 15 to 25%

Butane 0.3 to 4%

Propane 0.3 to 4%

A preferred composition mainly comprises:

R134a 10 to 35%

R125 79.8 to 25%

R143a 10 to 30%

Isobutane 0.1 to 5%

Propane 0.1 to 5%

A preferred composition mainly includes:

R134a 10 to 25%

R125 74.4 to 42%

R143a 15 to 25%

Isobutane 0.3 to 4%

Propane 0.3 to 4%

A preferred composition mainly includes:

R134a 10 to 35%

R125 79.7 to 20%

R143a 10 to 30%

Butane 0.1 to 5%

Isobutane 0.1 to 5%

Propane 0.1 to 5%

A preferred composition mainly includes:

R134a 10 to 25%

R125 74.1 to 38%

R143a 15 to 25%

Butane 0.3 to 4%

Isobutane 0.3 to 4%

Propane 0.3 to 4%

A preferred composition mainly includes:

R134a 15 to 20%

R125 67.4 to 53%

R143a 17 to 22%

Isobutane 0.3 to 3%

Propane 0.3 to 2%

A preferred composition mainly includes:

R134a 15 to 20%

R125 67.4 to 53%

R143a 17 to 22%

Butane 0.3 to 3%

Propane 0.3 to 2%

A preferred composition mainly includes:

R134a 16%

R125 60%

R143a 21%

Isobutane 2%

Propane 1%

A preferred composition mainly includes:

R134a 16%

R125 60%

R143a 21%

Butane 2%

Propane 1%

In one embodiment the amount of isobutane is from 0.6 to 4%, wherein when both the liquid and the gas of the composition are present in the same container, neither the gas phase nor the liquid phase is flammable.

In a second preferred embodiment the amount of hydrocarbons is 0.6 to 3.5%.

In a particularly preferred embodiment, the refrigerant composition that can replace R22 includes:

R134a 15.7%

R125 63%

R143a 18%

Butane 3.3%

Another preferred composition that can be used to replace R22 mainly includes:

R134a 15.8%

R125 63%

R143a 18%

Isobutane 3.2%

Another preferred refrigerant composition comprises:

R134a 15.9%

R125 63%

R143a 18%

Isobutane 3.1%

A preferred refrigerant composition comprises:

R134a 16%

R125 63%

R143a 18%

Isobutane 3%

Another preferred refrigerant composition comprises:

R134a 16.1%

R125 63%

R143a 18%

Isobutane 2.9%

Another preferred refrigerant composition comprises:

R134a 16.2%

R125 63%

R143a 18%

Isobutane 2.8%

Another preferred refrigerant composition comprises:

R134a 16.3%

R125 63%

R143a 18%

Isobutane 2.7%

Another preferred refrigerant composition comprises:

R134a 16.4%

R125 63%

R143a 18%

Isobutane 2.6%

Another preferred refrigerant composition comprises:

R134a 16.5%

R125 63%

R143a 18%

Isobutane 2.5%

Another preferred refrigerant composition comprises:

R134a 16%

R125 64%

R143a 18%

Isobutane 2%

Another preferred refrigerant composition comprises:

R134a 15.7%

R125 65%

R143a 16%

Isobutane 3.3%

Another preferred refrigerant composition comprises:

R134a 15.8%

R125 65%

R143a 16%

Isobutane 3.2%

Another preferred refrigerant composition comprises:

R134a 15.9%

R125 65%

R143a 16%

Isobutane 3.1%

Another preferred refrigerant composition comprises:

R134a 16%

R125 65%

R143a 16%

Isobutane 3%

Another preferred refrigerant composition comprises:

R134a 16.1%

R125 65%

R143a 16%

Isobutane 2.9%

Another preferred refrigerant composition comprises:

R134a 16.2%

R125 65%

R143a 16%

Isobutane 2.8%

Another preferred refrigerant composition comprises:

R134a 16.3%

R125 65%

R143a 16%

Isobutane 2.7%

Another preferred refrigerant composition comprises:

R134a 16.4%

R125 65%

R143a 16%

Isobutane 2.6%

Another preferred refrigerant composition comprises:

R134a 16.5%

R125 65%

R143a 16%

Isobutane 2.5%

Another preferred refrigerant composition comprises:

R134a 15.7%

R125 67%

R143a 14%

Butane 3.3%

Another preferred refrigerant composition comprises:

R134a 15.8%

R125 67%

R143a 14%

Isobutane 3.2%

Another preferred refrigerant composition comprises:

R134a 15.9%

R125 67%

R143a 14%

Isobutane 3.1%

Another preferred refrigerant composition comprises:

R134a 16%

R125 67%

R143a 14%

Isobutane 3%

Another preferred refrigerant composition comprises:

R134a 16.1%

R125 67%

R143a 14%

Isobutane 2.9%

Another preferred refrigerant composition comprises:

R134a 16.2%

R125 67%

R143a 14%

Isobutane 2.8%

Another preferred refrigerant composition comprises:

R134a 16.3%

R125 67%

R143a 14%

Isobutane 2.7%

Another preferred refrigerant composition comprises:

R134a 16.4%

R125 67%

R143a 14%

Isobutane 2.6%

Another preferred refrigerant composition comprises:

R134a 16.5%

R125 67%

R143a 14%

Isobutane 2.5%

Percentages and other ratios referred to in this specification, unless otherwise stated, are by weight and within the disclosed ranges are selected to give a total of 100%.

The invention is further illustrated by non-limiting examples. The following acronyms are used.

AF Formulated Mixed Composition

WCF WORST COMPOSITION: WCF is defined as a composition containing the highest amount (percentage) of flammable components and the least amount of non-combustible components within manufacturing tolerances.

WCFF Worst Fractionation Component: When a mixture leaks from a unit or system, one or more combustible components can concentrate in the liquid or gas phase due to fractionation. In order to properly assess whether the mixture has a possible fire hazard, the most adverse component (WCF) composition is subjected to the standard leak test specified in the ASHRAE34 protocol. This leak test can be experimental or can be simulated using a computer program such as NIST's Refleak.

example 1

The gaseous phase of a mixture consisting of 88% R134a, 10% R125 and 2% pentane was allowed to leak from the cylinder under isothermal conditions. Monitor the cylinder weight and analyze the liquid and gas phases of the mixture using gas-liquid chromatography. The first analysis is performed after 2% refrigerant loss. As shown in Table 1, each subsequent analysis was performed after 10% of the remaining refrigerant in the cylinder had leaked. Continue this experiment until no liquid remains in the cylinder.

Example 2

The AF combination is a mixture of 63% R125, 18% 143a, 16% R134a, 0.6% butane and 2.4% isobutane, and its WCF combination is 62% R125, 18.8% R143a, 16% R134a, 0.7% butane and 2.5 %Isobutane. The fractionation of the gas isothermal leakage of the WCF mixture at 54°C and -34.4°C was calculated using NIST's Refleak program. The WCFF compositions under these conditions are shown in Table 2.

Table 2

Example 3

The AF combination is a mixture of 63% R125, 18% 143a, 15.7% R134a and 3.3% isobutane, and its WCF combination is 62% R125, 18.9% R143a, 15.7% R134a and 3.4% isobutane. The fractionation of the gas isothermal leakage of the WCF mixture at 54°C and -34.4°C was calculated using NIST's Refleak program. The WCFF compositions under these conditions are shown in Table 3.

table 3

Example 4

Use the NIST Cycle D procedure to determine the values for R125, R143a, R134a, and R600a mixtures in a typical hermetic or semi-hermetic air conditioner.

Output cooling load 10kW

Evaporator

Midpoint evaporation temperature 7℃

Overheating 5.0℃

Suction line pressure drop (within saturation temperature) 1.5°C

condenser

Midpoint fluid condensation temperature 45.0℃

Supercooled 5.0℃

Discharge line pressure drop (within saturation temperature) 1.5℃

Liquid Line/Suction Line Heat Exchangers

Efficiency 0.3

compressor

Compressor Isentropic Efficiency 0.7

Compressor Volumetric Efficiency 0.82

Motor Efficiency 0.85

parasitic power

Evaporator fan 0.3kW

Condenser fan 0.4kW

Controller 0.1kW

The performance of the mixture in the air-conditioning unit was analyzed using these operating parameters and the results are shown in Table 4, with the addition of R22 as a control.

Example 5

Use the NIST Cycle D procedure to determine values for R125, R143a, R134a, and R600a mixtures in a typical open compressor refrigeration unit.

Output cooling load 10kW

Evaporator

Midpoint evaporation temperature -30℃

Overheating 5.0℃

Suction line pressure drop (within saturation temperature) 1.5°C

condenser

Midpoint fluid condensation temperature 35.0℃

Supercooled 5.0℃

Discharge line pressure drop (within saturation temperature) 1.5°C

Liquid Line/Suction Line Heat Exchangers

Efficiency 0.3

compressor

Compressor isentropic efficiency 0.7

Compressor Volumetric Efficiency 0.82

Motor Efficiency 0.85

parasitic power

Evaporator fan 0.3kW

Condenser fan 0.4kW

Controller 0.1kW

The results of analyzing the performance of the mixture in the air-conditioning unit using these operating parameters are shown in Table 5, with the addition of R22 and R502 as controls.

Claims (9)

1. A refrigerant composition consisting of the following components by weight: 2. The refrigerant composition as claimed in claim 1, which consists of the following components by weight: 3. The refrigerant composition as claimed in claim 1, which consists of one of the following compositions by weight: 4. The refrigerant composition of claim 1 which is permitted to leak under the conditions specified in ASHRAE Standard 34 without producing a liquid or gaseous mixture having a hydrocarbon content greater than 5% by weight. 5. The refrigerant composition of claim 1 which is permitted to leak under the conditions specified in ASHRAE Standard 34 without producing a liquid or gaseous mixture having a hydrocarbon content greater than 4% by weight. 6. The refrigerant composition of claim 1, wherein the weight percent of hydrocarbons does not change by more than 0.5% when the composition leaks at 23°C under isothermal gas. 7. A refrigerant composition as claimed in any one of the preceding claims for use in air conditioning units or refrigeration units together with mineral or alkylbenzene oils, synthetic hydrocarbons or oxygenated lubricants. 8. The refrigerant composition according to any one of claims 1-6, wherein the refrigerant composition is used in an air-conditioning unit or a refrigeration unit, wherein the lubricant is a mixture of a hydrocarbon and an oxygen-containing lubricant. 9. The refrigerant composition of any one of claims 1-6, wherein the refrigerant composition is used in a refrigeration unit wherein the lubricant is a mixture of a hydrocarbon and an oxygen-containing lubricant.